1236 DIPLODON 



swollen beaks, the furrow on the posterior slope and the size 

 and form of the cardinal teeth, which are peculiar in this. The 

 beaks of this specimen being" much eroded, it is impossible 

 to say what may be the character of the tips, but they are likely 

 to have rayed ribs, like most South American Unionidcc, but 

 not so much so as in wheatleyanus. The specimen before me, 

 as described above, is rugose, with a few irregular transverse 

 and radiating furrows, which may not exist on all specimens. 

 It is dark brown and roughly striate near the margin, and 

 smoother and ligrht brown towards the beaks." 



DiPi.ODOX GREJiPKEANUS (von Ihcring). 



"Shell sulcate, elliptical or suboblong, inequilateral, rather 

 compressed, rounded before, obtusely angulate behind ; valves 

 rather thick ; beaks not prominent, with accessor}^ radiate, 

 undulating striae on the posterior slope. Epidermis greenish- 

 brown, obsoletely radiate. Cardinal teeth long, lamellar rather 

 stout ; laterals long and somewhat curved. Nacre silvery, 

 moderately iridescent. 



Length 64, height 39, diam. 22 mm. Beaks situated at 1-4 

 of the length."' (von Thering). 



Sao Paulo, Brazil. 

 Unio greeifcaiuis von Thering. Arch, fiir Nat., 1893, P- 9^^ 



pi. IV, fig. 8. 

 Diplodon grcefiianns Simpson, Syn., 1900, p. 875. 



DiPi.ODON PiGEK (Lea). 



Shell subrhomboid or obovate, subsolid, inflated, inequilat- 

 eral, with full liut lov.' beaks, having radial sculpture ; post- 

 dorsal part slightly winged, the wing ending in an angle caused 

 by the truncation of the posterior slope ; posterior ridge well 

 developed, subangular, ending behind in a blunt point near 

 the base of the shell ; base and anterior end rounded, the latter 

 with an obfuse angle above ; surface with fine concentric sculp- 

 ture ; epidermis olive, feebly banded, scarcely shining; left 

 valve with one comi)re''-sed pseudocardinal and a vestige of 

 another in front of it. v\ith two delicate, curved laterals, the 



